Composite valve

ABSTRACT

A composite valve has a communication path, a second valve port and a pilot passage. First and second valve bodies are arranged to be moved up and down in the same direction, and are away from each other only at a predetermined distance. In the case that a lift amount of the second valve body for a small flow rate control is equal to or less than a predetermined amount, said pilot passage and a first valve port are respectively closed by a pilot valve body and the first valve body, thereby taking a small flow rate control state. In the case that the lift amount of said second valve body goes beyond said predetermined amount, said pilot valve body is moved up by the upward movement of a valve shaft to open said pilot passage, thereby taking a large flow rate control state.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a composite valve which is preferablyused in a heat pump type cooling and heating system or the like, andmore particularly to a composite valve which is provided with a pilottype large flow rate control valve and a small flow rate control valve.

2. Description of the Conventional Art

As a heat pump type cooling and heating system, there has beenconventionally known a structure which is provided with a compressor, acondenser, an evaporator, an expansion valve and a four-way valve forconverting (inverting) a refrigerant flow path.

On the other hand, as a heat pump type cooling and heating system for avehicle (for example, for an electric vehicle), there has been proposeda system which does not invert a flow of a refrigerant and is providedindependently with an expansion valve for cooling and an expansion valvefor heating, for example, as shown in FIG. 1 of Japanese OfficialGazette of Patent No. 3799732.

The flow of the refrigerant is not inverted in the system mentionedabove. Accordingly, for example, paying attention to an expansion valvefor heating (reference numeral 24) shown in FIG. 1 of Japanese PatentNo. 3799732, it is structured such that an electromagnetic valve forcooling (reference numeral 26) is provided in parallel to the expansionvalve for heating, the electromagnetic valve for cooling is closed andthe refrigerant is narrowed down by means of the expansion valve forheating at a time of heating, and the expansion valve does not carry outthe narrowing down of the refrigerant by setting the electromagneticvalve for cooling open and bypassing the inlet and outlet of theexpansion valve for heating at a time of cooling.

In the meantime, if the expansion valve and the electromagnetic valvefor bypassing are respectively provided for cooling and for heating, thesystem is enlarged in size, a piping assembling cost or the like becomeshigh, and there is a risk that an electric power consumption isenlarged.

Accordingly, it is thought to achieve these functions by oneelectrically operated valve. In other words, for example, therefrigerant may be narrowed down by the electrically operated valve at atime of heating, and the electrically operated valve may be fully openedat a time of cooling.

In this case, a description will be given of one example of aconventional electrically operated valve with reference to FIG. 4.

An electrically operated valve 1′ in an illustrated example is providedwith a valve shaft 25 which has a lower shaft portion 25 a and an uppersmall diameter shaft portion 25 b, a valve main body 40 which has avalve chamber 41, a can 60 which is bonded in a sealing manner to thevalve main body 40 in its lower end portion, a rotor 30 (a rotating axisO) which is arranged in an inner periphery of the can 60 so as to bespaced at a predetermined gap α, and a stator 50A which is outwardfitted to the can 60 so as to rotationally drive the rotor 30.

The valve shaft 25 is integrally provided with a valve body portion 44having a specific shape (two stages of inverted circular truncated coneshapes respectively having predetermined angles of center) in a lowerend portion of the lower shaft portion 25 a, and the presentelectrically operated valve 1′ is structured such that a passing flowrate of the refrigerant is controlled by changing a lift amount of thevalve body portion 44.

The valve chamber 41 of the valve main body 40 is provided in its lowerportion with a valve seat 42 with a valve port (an orifice) 43 which thevalve body portion 44 comes close to and away from, and is opened in itsside portion to a first inlet and outlet 5′, and a lower portion of thevalve main body 40 is provided with a second inlet and outlet 6′ so asto be connected to the valve port 43.

The stator 50A is constructed by a yoke 51, a bobbin 52, a stator coil53, a resin mold cover 56 and the like, a stepping motor 50 isconstructed by the rotor 30, the stator 50A and the like, and anelevation driving mechanism for regulating a lift amount (=an openingdegree) of the valve body portion 44 with respect to the valve port 43is constructed by the stepping motor 50, a feed screw (a female threadportion 38 and a male thread portion 48) mentioned below and the like.

A support ring 36 is integrally connected to the rotor 30, and an upperprotruding portion of a lower opened and tubular valve shaft holder 32which is arranged in an outer periphery of a guide bush 46 is fixed, forexample, by caulking to the support ring 36, whereby the rotor 30, thesupport ring 36 and the valve shaft holder 32 are integrally connected.

Further, a lower end portion of the tubular guide bush 46 is pressedinto and fixed to a fitting hole 49 which is provided in an upperportion of the valve main body 40, and (the lower shaft portion 25 a of)the valve shaft 25 is inward inserted slidably to the guide bush 46.Further, in order to move up and down the valve shaft 25 (the valve bodyportion 44) by utilizing a rotation of the rotor 30, the male threadportion 48 is formed in an outer periphery of the guide bush 46, thefemale thread portion 38 is formed in an inner periphery of the valveshaft holder 32, and the feed screw is constructed by the male threadportion 48 and the female thread portion 38.

Further, an upper small diameter portion 46 b of the guide bush 46 isinward inserted to an upper portion of the valve shaft holder 32, andthe upper small diameter shaft portion 25 b of the valve shaft 25 isinserted to (a through hole formed in) the center of a ceiling portionof the valve shaft holder 32. A push nut 33 is pressed into and fixed toan upper end portion of the upper small diameter shaft portion 25 b ofthe valve shaft 25.

Further, the valve shaft 25 is outward inserted to the upper smalldiameter shaft portion 25 b of the valve shaft 25, and is normallyenergized downward (in a valve closing direction) by a valve closingspring 34 constructed by a compression coil spring which is installed ina compression manner between a ceiling portion of the valve shaft holder32 and an upper end terrace surface of the lower shaft portion 25 a inthe valve shaft 25. A restoring spring 35 constructed by a coil springis provided in an outer periphery of the push nut 33 on the ceilingportion of the valve shaft holder 32.

To the guide bush 46, there is firmly fixed a lower stopper body (afixing stopper) 47 which constructs one of rotation and downwardmovement stopper mechanisms for inhibiting a further rotation anddownward movement at a time when the rotor 30 is rotated and moveddownward to a predetermined valve closing position, and to the valveshaft holder 32, there is firmly fixed an upper stopper body (a movablestopper) 37 which constructs another of the stopper mechanisms.

In this case, the valve closing spring 34 is arranged for obtaining adesired seal pressure in a valve closed state in which the valve bodyportion 44 seats on the valve port 43 (preventing a leakage), and forreducing an impact at a time when the valve body portion 44 comes intocontact with the valve port 43.

In the electrically operated valve 1′ structured as mentioned above, therotor 30 and the valve shaft holder 32 are rotated in one direction withrespect to the guide bush 46 which is fixed to the valve main body 40,by supplying an electrifying and exciting pulse to the motor 50 (thestator 50A) in accordance with a first mode, and on the basis of a screwfeeding of the thread portions 48 and 38, for example, the valve shaftholder 32 moves downward, the valve body portion 44 is pressed to thevalve seat 42, and the valve port 43 is closed.

At a time point when the valve port 43 is closed, the upper stopper body37 has not come into contact with the lower stopper body 47 yet, and therotor 30 and the valve shaft holder 32 further rotate and move downwardwhile the valve body portion 44 closes the valve port 43. In this case,since the valve shaft 25 (the valve body portion 44) does not movedownward, however, the valve shaft holder 32 moves downward, the valveclosing spring 34 is compressed at a predetermined amount. As a result,the valve body portion 44 is strongly pressed to the valve seat 43, theupper stopper body 37 comes into contact with the lower stopper body 47on the basis of the rotation and the downward movement of the valveshaft holder 32, and the rotation and the downward movement of the valveshaft holder 32 are forcibly stopped even if the pulse supply withrespect to the stator 50A is thereafter carried on (a fully closedstate).

On the other hand, if the electrifying and exciting pulse is supplied inaccordance with a second mode to the stator 50A from this fully closedstate, the rotor 30 and the valve shaft holder 32 are rotated in areverse direction to that mentioned above with respect to the guide bush46 which is fixed to the valve main body 40, and the valve shaft holder32 moves upward this time on the basis of the screw feeding of thethread portions 48 and 38. In this case, since the valve closing spring34 is compressed at the predetermined amount as mentioned above, at atime point of starting the rotation and the upward movement of the valveshaft holder 32 (a time point of starting the pulse supply), the valvebody portion 44 is not disconnected from the valve seat 42 and remainsin the valve closed state (a lift amount=0) until the valve closingspring 34 extends at the predetermined amount mentioned above. Further,if the valve shaft holder 32 is further rotated and moved upward afterthe valve closing spring 34 extends at the predetermined amount, thevalve body portion 24 is disconnected from the valve seat 42 and thevalve port 43 is opened, so that the refrigerant passes through thevalve port 43.

In this case, it is possible to optionally and finely regulate the liftamount of the valve body portion 44, in other words, an effectiveopening area (=an opening degree) of the valve port 43 on the basis ofan amount of rotation of the rotor 30. Further, since the amount ofrotation of the rotor 30 is controlled by a supply pulse number, it ispossible to control a flow rate of the refrigerant at a high precision.

Accordingly, in the case that the electrically operated valve 1′ havingthe structure mentioned above is employed as the electrically operatedvalve having both functions of the expansion valve and theelectromagnetic valve for bypassing shown in the Japanese OfficialGazette of Patent No. 3799732 mentioned above, it is set to a maximumopening degree (a maximum lift amount) in such a manner as to reduce thepressure loss as much as possible so as to serve as the electromagneticvalve for bypassing, for example, at a time of the cooling operation,and it is set such as to finely control the opening degree (the liftamount) so as to serve as the expansion valve and finely control thevalve opening degree, that is, the flow rate of the refrigerant, forexample, at a time of the heating operation.

However, in the electrically operated valve 1′, an improvement of a flowrate control precision in the small flow rate region and an increase ofa controllable flow rate come to an antimony. In other words, in orderto make the electrically operated valve 1′ serve as the expansion valve,it is necessary to secure a high flow rate control precision in thesmall flow rate region. Since it is demanded to make a resolving powerof the flow rate control high for this purpose, it is necessary to makea valve bore diameter (an effective opening area) as small as possible.On the contrary, in order to make it serve as the electromagnetic valvefor bypassing, since it is demanded to suppress the pressure loss as lowas possible, the valve bore diameter can not be made so small (smallerthan an effective passage cross sectional area of a piping system). Inother words, if the valve bore diameter is made smaller, it is possibleto make the flow rate control precision in the small flow rate regionhigh, however, if it is intended to increase a flow rate (a controllableflow rate) of the refrigerant which is circulated to the system, thevalve port portion comes to a resistance and the pressure loss isenlarged even if the valve opening degree is made maximum. On thecontrary, if the valve bore diameter is enlarged, the increase of thecontrollable flow rate (the reduction of the pressure loss) can beachieved, however, the flow rate control precision in the small flowrate region is lowered. In addition, it is necessary to enlarge thevalve body or the like in correspondence to the valve bore diameter, agreat torque is necessary for driving the valve body, and there is arisk that an enlargement in size and an increase of an electric powerconsumption are caused.

Further, if the resolving power is made higher in order to achieve animprovement of the flow rate control precision in the small flow rateregion (for example, the valve body lift amount per one rotation of therotor is made smaller), it takes a long time to reach a full open state(a flow path bypass state) from the small flow rate control state, andan opening gap (a gap between the valve body portion and the valve portwall surface) at a time of the small flow rate control becomes verynarrow, so that there is a risk that a foreign material or the like isbitten into the gap so as to be clogged.

Accordingly, in order to achieve both an improvement of a flow ratecontrol precision and an increase of a controllable flow rate (areduction of the pressure loss) in the small flow rate region, achieve areduction of a time required for reaching the full open state from thesmall flow rate control state and achieve a reduction of an electricpower consumption, the following Japanese Official Gazette of Patent No.4416528 discloses a provision of a pilot type first control valve (afirst valve body and a first valve port) for a large flow rate and asecond control valve (a second valve body and a second valve port) for asmall flow rate, in more detail, a composite valve structured such as toopen and close the first valve port having a large bore diameter by thepiston type first valve body, open and close the second valve porthaving a small bore diameter by the needle type second valve body whichis an independent body from the first valve body and is provided in thelower portion of the valve shaft (25), and make the second control valvefor the small flow rate serve as the pilot valve of the first controlvalve for the large flow rate.

In this composite valve, when the lift amount of the valve shaft (thesecond valve body) is equal to or less than a predetermined amount (whenthe second control valve opening degree is equal to or less than apredetermined value), there is established a small flow rate controlstate in which the first valve body closes the first valve port, and thesecond control valve opening degree for the small flow rate iscontrolled by the second valve body. At this time, the refrigerant at anamount corresponding to the lift amount (the second control valveopening degree) of the second valve body flows to the inflow port→thefirst valve chamber→the gap of the sliding surface formed between theouter peripheral surface of the first valve body and the wall surface ofthe fitting and inserting chamber→the back pressure chamber→the pilotpassage→the second valve chamber→the second valve port→the outflowpassage→the outflow port. Further, if the lift amount of the valve shaft(the second valve body) goes beyond the predetermined amount, the amountof the refrigerant flowing out of the back pressure chamber via thesecond valve port is increased in comparison with the small flow ratecontrol time, the pressure of the back pressure chamber is lowered, andthe valve opening force becomes finally larger than the valve closingforce acting on the first valve body, whereby the first valve body opensthe first valve port, and there is established a large flow rate controlstate in which the refrigerant flows to the inflow port→the first valvechamber→the first valve port→the outflow port.

As mentioned above, it is possible to achieve both the improvement ofthe flow rate control precision in the small flow rate region and theincrease of the controllable flow rate (the reduction of the pressureloss), and the low electric power consumption, by opening and closingthe first valve port having the large bore diameter by means of thefirst valve body, opening and closing the second valve port having thesmall bore diameter by means of the second valve body, and making thesecond valve body serve as the pilot valve of the first control valvefor the large flow rate.

However, in the composite valve described in the Japanese OfficialGazette of Patent No. 4416528 mentioned above, since the single secondcontrol valve for the small flow rate serves as the control valve forthe small flow rate region and the pilot valve with respect to the firstcontrol valve for the large flow rate, there is a risk that thefollowing problem is generated. In other words, since it is necessary towidely increase the flow rate of the refrigerant passing through thesecond control valve for the small flow rate in comparison with thesmall flow rate control time, in order to switch from the small flowrate control to the large flow rate control, it is necessary to set thebore diameter (the effective opening area) of the second valve portsignificantly larger than the bore diameter which is necessary for thesmall flow rate control. Accordingly, an increase of a motion load, andan enlargement in size of a driving portion (a motor portion) and avalve main body tend to be caused, and a dimensional and a shape of thesecond control valve for the small flow rate can not be set to thosewhich are optimum for the small flow rate control, so that there is sucha problem that a flow rate control precision at a time of the small flowrate control can not be enhanced very much.

Further, since the opening and closing of the first control valve forthe large flow rate depends on the lift amount of the second valve bodychanging subtly, there is not a little a case that the opening andclosing of the first control valve for the large flow rate is notcarried out at a desired timing. Further, since the refrigerant iscirculated via the sliding surface gap of the first valve body→the backpressure chamber→the pilot passage at a time of the small flow ratecontrol, there is such a problem that a malfunction caused by a smallforeign material mixing into the refrigerant (for example, the lockingof the first valve body caused by the biting of the small foreignmaterial into the sliding surface gap) tends to be generated.

Accordingly, the inventors of the present invention has previouslyproposed the composite valve as described in Japanese Patent ApplicationNo. 2011-68451 (Patent Application Date: Mar. 25, 2012), for dissolvingthe problem mentioned above. The composite valve is provided with apiston type first valve body, a valve shaft provided with a needle typesecond valve body, an elevation driving means for moving up and down thevalve shaft, a pilot valve body driven so as to be opened and closed byutilizing the elevating motion of the valve shaft, and a valve main bodyprovided with an inflow port and an outflow port, and is structured suchthat between the inflow port and the outflow port in the valve mainbody, there are provided a fitting and inserting chamber to which thefirst valve body is slidably fitted and inserted, and which is zonedinto a back pressure chamber and a first valve chamber by the firstvalve body, a first valve port which is open to the first valve chamber,a second valve chamber in which the pilot valve body and the secondvalve body are arranged so as to be movable up and down, a second valveport which communicates the inflow port or the first valve chamber withthe second valve chamber, and a pilot passage which communicates theback pressure chamber with the second valve chamber, and such that inthe case that a lift amount of the second valve body is equal to or lessthan a predetermined amount, the pilot passage is closed by the pilotvalve body, and the first valve port is closed by the first valve body,thereby taking a small flow rate control state in which a flow rate iscontrolled in correspondence to the lift amount of the second valvebody, and in the case that the lift amount of the second valve body goesbeyond the predetermined amount, the pilot valve body is moved up inconjunction with the upward movement of the valve shaft so as to openthe pilot passage, thereby taking a large flow rate control state inwhich the first valve body opens the first valve port on the basis ofthis. In this composite valve, an actuator for moving up and down thevalve shaft 25 as described with regard to FIG. 4 can be used as anelevating means of the valve shaft which is provided with the secondvalve body.

In the proposed composite valve mentioned above, the second valve bodyfor the small flow rate control is provided independently from the pilotvalve body for driving the first valve body for the large flow ratecontrol, the second valve body carries out the small flow rate controluntil the second valve body lifts up at a predetermined amount, and thepilot valve body is drawn up at a state that the second valve body liftsup at the predetermined amount so as to drive the first valve body.Accordingly, it is possible to set the dimension and the shape of thesecond control valve for the small flow rate (the second valve body) soas to be optimum for the small flow rate control, and it is possible tosecurely carry out the opening and closing of the first control valvefor the large flow rate (the first valve body) at a desired timing.Further, there can be achieved such an excellent effect that it ispossible to make the malfunction hard to be generated.

SUMMARY OF THE INVENTION

However, in the composite valve described in the Japanese PatentApplication No. 2011-68451 mentioned above, there has been the followingproblem to be improved. In other words, since a high pressure from thefirst valve chamber is applied to the second valve body in the valveclosed state in a direction of opening the valve through the secondvalve port (a pushing up direction), it is necessary to use a valveclosing spring having a significantly large spring load as a valveclosing spring (reference numeral 34 in FIG. 4) which energizes thesecond valve body (the valve shaft) in the valve closing direction inorder to prevent the second valve body from undesirably opening thevalve (maintain the second control valve for the small flow rate in thevalve closed state), and the bore diameter of the second valve port isconstrained.

If the valve closing spring having the large spring load is used, it isnecessary to use an electrically operated motor which generates thecorresponding driving torque, in order to lift up the second valve bodyagainst the energizing force of the valve closing spring, therebycausing a cost increase, an enlargement in size of a whole valve, anincrease of an electric power consumption and the like. Further, if thebore diameter of the second valve port is constrained as mentionedabove, it becomes hard to achieve both the improvement of the flow ratecontrol precision in the small flow rate region and the improvement ofthe controllable flow rate (the reduction of the pressure loss).

The present invention is made by taking the actual condition mentionedabove into consideration, and an object of the present invention is toprovide a composite valve which is provided with a pilot type firstcontrol valve for a larger flow rate and a second control valve for asmall flow rate, for achieving both an improvement of a flow ratecontrol precision in a small flow rate region and an increase of acontrollable flow rate (a reduction of a pressure loss), can set adimension and a shape of the second control valve for the small flowrate to those which are optimum for a small flow rate control, cansecurely prevent a second valve body from being undesirably opened, andcan achieve a cost reduction, a downsizing, a reduction of an electricpower consumption and the like.

In order to achieve the object mentioned above, a composite valve inaccordance with the present invention is basically comprising:

a first valve body;

a valve shaft which is provided with a second valve body;

an elevation driving means for moving up and down the valve shaft;

a pilot valve body which is driven so as to be opened and closed byutilizing an elevating motion of the valve shaft; and

a valve main body which is provided with an inflow port and an outflowport,

wherein between the inflow port and the outflow port in the valve mainbody, there are provided a fitting and inserting chamber to which thefirst valve body is slidably fitted and inserted, and which is zonedinto a back pressure chamber and a first valve chamber by the firstvalve body, a first valve port which is open to the first valve chamber,a second valve chamber in which the pilot valve body and the secondvalve body are arranged so as to be movable up and down, a communicationpath which communicates the inflow port or the first valve chamber withthe second valve chamber, a second valve port which communicates thesecond valve chamber with the outflow port, and a pilot passage whichcommunicates the back pressure chamber with the outflow port,

wherein the first valve body and the valve body are arranged in such amanner as to be moved up and down in the same direction, and are awayfrom each other only at a predetermined distance, and

wherein in the case that a lift amount of the second valve body is equalto or less than a predetermined amount, the pilot passage is closed bythe pilot valve body, and the first valve port is closed by the firstvalve body, thereby taking a small flow rate control state in which aflow rate is controlled in correspondence to the lift amount of thesecond valve body, and in the case that the lift amount of the secondvalve body goes beyond the predetermined amount, the pilot valve body ismoved up in conjunction with the upward movement of the valve shaft soas to open the pilot passage, thereby taking a large flow rate controlstate in which the first valve body opens the first valve port.

In accordance with a preferable aspect, the pilot valve is energizeddownward by a spring member so as to close the pilot passage, and ispulled up against the energizing force of the spring member by a catchportion which is provided in the valve shaft, if the lift amount of thesecond valve body is increased further more than the predeterminedamount.

In accordance with the other preferable aspect, the first valve body isprovided with a pressure equalizing hole which communicates the firstvalve chamber with the back pressure chamber.

Since the composite valve in accordance with the present invention isprovided with the pilot valve body which is independent from the secondvalve body, in addition to the first control valve for the large flowrate (the first valve body and the first valve port), and the secondcontrol valve for the small flow rate (the second valve body and thesecond valve port), and is structured such as to drive the pilot valvebody so as to open and close by utilizing the elevating motion of thevalve shaft which is provided with the second valve body, it is possibleto set the dimension and the shape of the second control valve for thesmall flow rate (the second valve body and the second valve port) so asto be optimum for the small flow rate control, and it is possible tosecurely carry out the opening and closing of the first control valvefor the large flow rate at a desired timing. Further, since thestructure is made such as to circulate the refrigerant without passingthrough the narrow portion such as the sliding surface gap or the likeas is different from the conventional one, at a time of controlling thesmall flow rate, it is possible to make the malfunction hard to begenerated. As a result, it is possible to achieve both an improvement ofthe flow rate control precision in the small flow rate region, and anincrease of the controllable flow rate (a reduction of the pressureloss), without causing an increase of a motion load, and an enlargementin size of the driving portion (the motor portion) and the valve mainbody.

In addition, in the composite valve in accordance with the presentinvention, since the second valve port which is opened and closed by thesecond valve body is communicated with the outflow port and thecomposite valve, is provided with the vertical hole communication pathwhich communicates the inflow port or the first valve chamber with thesecond valve chamber, and is structured such that the high pressure inthe first valve chamber is introduced into the second valve chamber, avalve closing force (a pushing down force) acting on the second valvebody in the valve closing state becomes significantly larger than aforce which is going to push up it. Therefore, it is possible tosecurely prevent the second valve body from opening the valveundesirably without enlarging the spring load of the valve closingspring which energizes the second valve body (the valve shaft) in thevalve closing direction, and it is possible to reduce the constraintwith respect to the bore diameter of the second valve port or the like.As a result, it is possible to achieve a cost reduction, a downsizingand a reduction of an electric power consumption.

Further, in the composite valve in accordance with the presentinvention, since the pilot valve body is arranged in the second valvechamber to which the high pressure of the first valve chamber isintroduced, the high pressure is applied to the other portions than apilot valve seat occluded portion in the pilot valve body. Accordingly,it is possible to securely prevent the pilot valve body from opening thevalve undesirably without enlarging the spring load of the spring whichenergizes the pilot valve body in the direction of closing the pilotpassage. As a result, it is possible to reduce the constraint withrespect to an inner diameter of the pilot passage 19 and a bore diameterof the pilot valve seat, so that it is possible to achieve a costreduction, a downsizing, a reduction of the electric power consumptionand the like

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a vertical cross sectional view of a substantial part andshows a first motion state (a fully closed state) in an embodiment of acomposite valve in accordance with the present invention;

FIG. 2 is a vertical cross sectional view of a substantial part andshows a second motion state (a small flow rate control state) in theembodiment of the composite valve in accordance with the presentinvention;

FIG. 3 is a vertical cross sectional view of a substantial part andshows a third motion state (a large flow rate control state) in theembodiment of the composite valve in accordance with the presentinvention; and

FIG. 4 is a vertical cross sectional view showing an example of aconventional electrically operated valve.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

A description will be given below of an embodiment in accordance withthe present invention with reference to the accompanying drawings.

FIGS. 1 to 3 are enlarged cross sectional views of a substantial partand show an embodiment of a composite valve in accordance with thepresent invention, in which the respective drawings show differentmotion states. Since a stepping motor (an actuator) 50 portion of acomposite valve 1 in accordance with the illustrated embodiment isapproximately the same as that of the conventional electrically operatedvalve 1′ shown in FIG. 4, the portion is omitted.

The composite valve 1 in accordance with the illustrated firstembodiment is provided with a rectangular parallelepiped valve main body10 which is larger than the valve main body 40 (FIG. 4) of theelectrically operated valve 1′ in the conventional example, a pilot typefirst control valve 4A for a larger flow rate (a first valve body 15 anda first valve port 13), a second control valve 4B for a small flow rate(a second valve body 24 and a second valve port 23), and a pilot valve4C (a pilot valve body 20, a pilot valve body retaining member 27, apilot passage 19 and a pilot valve body fitting and inserting hole 19D)which controls a driving of the first control valve 4A for the largeflow rate, for achieving both an improvement of a flow rate controlprecision in a small flow rate region and an increase of a controllableflow rate (a reduction of a pressure loss), and the first control valve4A for the large flow rate and the second control valve 4B for the smallflow rate are both arranged vertically (in such a manner that the firstvalve body 15 and the second valve body 24 are moved up and down in adirection which is parallel to a center axis O of the second valve body24), and are away from each other in a transverse direction only at apredetermined distance.

In detail, the valve main body 10 is provided with the inflow port 5transversely in the vicinity of the center of one side, is provided withthe outflow port 6 transversely in a lower portion of the other side, isprovided with the stepped concave hole 7 which is open in its uppersurface slightly closer to the right in the upper portion, and isprovided with the stepped downward vertical hole 8 which is open in itslower surface adjacently on the right of the inflow port 5 in the lowerside of the concave hole 7.

A bush retention body 28 corresponding to an upper portion of the valvemain body 40 (FIG. 4) in the conventional electrically operated valve 1′is fixed by screw to an upper half portion of the stepped concave hole7, a second valve chamber 21 is defined in a lower side than a cylinderportion 28 b with ceiling surface which is provided in a lower halfportion of the bush retention body 28 in the concave hole 7, and thecenter of a bottom portion of the concave hole 7 is provided with asecond valve seat 22 with a second valve port 23 which has a small borediameter in which a second valve body 24 is provided in a lower portionof a lower shaft portion 25 a of a valve shaft 25 which is driven so asto move up and down by the motor 50 comes close to and away from. Thesecond valve port 23 is provided so as to extend in a verticaldirection, and is opened in its lower end to an upper surface portion ofthe outflow port 6.

An upper end of a vertical hole communication path 29 which communicatesthe first valve chamber 11 and the second valve chamber 21 mentionedlater is open to the left side of the second valve port 23 in the bottomportion of the concave hole 7, and the pilot valve body fitting andinserting hole 19D to which a lower portion of a pilot valve 20 isslidably fitted and inserted is provided in the right side of the secondvalve port 23 in the bottom portion of the concave hole 7.

A valve seat member 12A which has a first valve seat 12 with a firstvalve port 13 having a large bore diameter is fixed by screw to aportion which is somewhat lower than the inflow port 5 in the steppeddownward vertical hole 8. Further, a lower portion of the downwardvertical hole 8 is open to the outflow port 6, and a lower end portionthereof is occluded by a blank cap 9.

An upper side than the valve seat member 12A in the downward verticalhole 8 is formed as a fitting and inserting chamber 14 with a ceilingsurface 14 a to which (a large diameter portion 15 a of) a piston typefirst valve body 15 is slidably fitted and inserted, the back pressurechamber 16 is defined in an upper side than (the large diameter portion15 a of) the first valve body 15 in the fitting and inserting chamber14, and the first valve chamber 11 is defined in a lower side than (thelarge diameter portion 15 a of) the first valve body 15.

The first valve body 15 has a bobbin-like outer shape in cross sectionhaving the large diameter portion 15 a and the small diameter portion 15b, an annular seal member 15 c which comes close to and away from thefirst valve seat 12 so as to open and close the first valve port 13, andis made of a rubber or a Teflon (trade mark) or the like is fixed to alower end portion thereof in accordance with an appropriate method suchas a caulking or the like, an upper end surface portion thereof isprovided in a protruding manner with a short cylindrical stopper 15 dwith a transverse hole 15 i which comes into contact with the ceilingsurface 14 a of the fitting and inserting chamber 14 so as to define anupward moving limit of the first valve body 15, and a seal member (apiston ring) 15 f is installed to an outer periphery of the largediameter portion 15 a.

Further, a first valve closing spring 18 constructed by a compressioncoil spring is installed in a compression manner between a bottomsurface of a spring bearing hole 15 h which is provided in the center ofan upper portion of the first valve body 15 and the ceiling surface 14 aof the fitting and inserting chamber 14, in order to energize the firstvalve body 15 downward (in a valve closing direction).

Further, a transverse penetrating path 15 g is provided in the smalldiameter portion 15 b of the first valve body 15, and a pressureequalizing hole 17 for communicating the first valve chamber 11 with theback pressure chamber 16 via the transverse penetrating path 15 g isprovided in a center portion thereof.

In this case, the transverse penetrating path 15 g is not alwaysnecessary (is effective in the case that the first valve chamber 11 isnarrow), but the structure may be made such that the first valve chamber11 and the back pressure chamber 16 are communicated directly by thepressure equalizing hole 17 by doing away with the transversepenetrating path 15 g.

In this case, in the composite valve 1 in accordance with the presentembodiment, on the assumption that a pressure of the first valve chamber11 is set to P1, a pressure of the back pressure chamber 16 is set toP2, a pressure of the first valve port 13 is set to P3, a horizontalcross sectional area of the back pressure chamber 16 (a pressure bearingarea of the first valve body 15) is set to Ap, a horizontal crosssectional area of the first valve port 13 is set to Av, an energizingforce of the main valve opening spring 18 is set to Pf, a force pushingup the first valve body 15 is set to a valve opening force, and a forcepushing down the first valve body 15 is set to a valve closing force, avalve opening condition of the first control valve for the large flowrate is as follows.Valve closing force=P2×Ap+Pf<valve opening force=P1×(Ap−Av)+P3×Av

On the other hand, in the second valve chamber 21, there are arranged acollared round bar pilot valve body 20 which is driven so as to beopened and closed by utilizing an elevating motion of the valve shaft 25(the second valve body 24) and has a semispherical valve body portion 20a and a collar portion 20 b, and a pilot valve body retention member 27which retains the pilot valve body 20. The pilot valve body retentionmember 27 is constructed by an upper side portion 27 a which is slidablyoutward inserted to the lower shaft portion 25 a of the valve shaft 25,a small diameter cylinder portion 27 b which is connected to a lowerside of the upper side portion 27 a, a large diameter cylinder portion27 c which is connected to a lower side of the small diameter cylinderportion 27 b, and a valve body support portion 27 d which protrudesoutward in a radial direction from the large diameter cylinder portion27 c, and the pilot valve body 20 is fitted and inserted to an insertionhole 27 e which is formed in the valve body support portion 27 d,whereby the collar portion 20 b provided in an upper portion thereof islocked so as to be prevented from coming off.

An intermediate large diameter portion 25 f with a retaining shouldersurface (a terrace surface) 25 b which is smaller in diameter than thesecond valve body 24 and larger in diameter than the lower shaft portion25 a is provided just above the second valve body 24 in the valve shaft25, and the upper side portion 27 a of the pilot valve body retentionmember 27 is put on a shoulder surface (a terrace surface) 25 h of thesecond valve body 24 in an outer periphery of the intermediate largediameter portion 25 f via a bearing coil spring 26B in a state of beingoutward inserted slidably to the lower shaft portion 25 a. In this case,the retaining shoulder surface 25 g of the intermediate large diameterportion 25 f comes to a catch portion for pulling up the pilot valvebody 20 via the pilot valve body retention member 27.

The lower portion of the pilot valve body 20 is slidably fitted andinserted to the pilot valve body fitting and inserting hole 19D. A lowerend portion of the pilot valve body fitting and inserting hole 19Dconstructs a part of the pilot passage 19 (having the upstreamtransverse hole 19 a and the downstream vertical hole 19 b) forreleasing the pressure in the back pressure chamber 16 to the outflowport 6, and is structured such as to open and close the pilot passage 19(an upper end opening of the downstream vertical hole 19 b which is opento a bottom surface of the pilot valve body fitting and inserting hole19D) by the semispherical valve body portion 20 a of the pilot valvebody 20. The upstream transverse hole 19 a is formed so as to be curvedto the far side with respect to the paper surface in FIG. 1 or as aC-shaped form, in such a manner to be prevented from cutting across thevertical hole communication path 29 and the second valve port 23.

Further, between the collar portion 20 b of the pilot valve body 20 andthe ceiling surface 21 a of the second valve chamber 21, there isprovided in a compression manner a pilot valve closing spring 26A whichenergizes the pilot valve body 20 retained by the pilot valve bodyretention member 27 so as to be prevented from coming off, downward (thevalve closing direction) together with the pilot valve body retentionmember 27A, and has a greater spring load than the bearing coil spring26B.

Accordingly, when the valve shaft 25 (the second valve body 24) is atthe maximum downward moving position (a lift amount is 0) which closesthe second valve port 23 as shown in FIG. 1, the semispherical valvebody portion 20 a of the pilot valve body 20 is pressed to the upper endopening of the downstream vertical hole 19 b which is open to the bottomsurface of the pilot valve body fitting and inserting hole 19D on thebasis of the energizing force of the pilot valve closing spring 26A soas to close the pilot passage 19.

If the lift amount of the valve shaft 25 (the second valve body portion24) goes beyond the predetermined amount Tc, the retaining shouldersurface 25 g of the intermediate large diameter portion 25 f comes intocontact with the lower surface of the upper side portion 27 a of thepilot valve body retention member 27, whereby the pilot valve bodyretention member 27 and the pilot valve body 20 are pulled up againstthe energizing force of the pilot valve closing spring 26A so as to openthe pilot passage 19. In other words, the pilot valve body 20 isstructured such as to be driven so as to be opened and closed byutilizing the elevating motion of the valve shaft 25.

In the composite valve 1 structured as mentioned above, since the highpressure refrigerant which is introduced into the first valve chamber 11from the inflow port 5 is introduced into the back pressure chamber 16via the transverse penetrating path 15 g and the pressure equalizinghole 17, and the pressure of the back pressure chamber 16 becomes a highpressure, in the case that the first valve body 15, the second valvebody 24 and the pilot valve body 20 are all in the closed state, asshown in FIG. 1, the first valve body 15 is strongly pressed to thefirst valve seat 12.

If the valve shaft 25 (the second valve body 24) is moved up by carryingout a pulse supply to the motor 50 from this state, the second valveport 23 is opened as shown in FIG. 2. In this case, in the case that alift amount of the second valve body 24 is equal to or less than thepredetermined amount Tc, the spring load of the pilot valve closingspring 26A is larger than the spring load of the bearing coil spring26B. Therefore, the bearing coil spring 26B is compressed on the basisof the rise of the second valve body 24, however, the pilot valve bodyretention member 27 and the pilot valve body 27 do not move.Accordingly, the pilot passage 19 remains closed by the pilot valve body27, and the first valve port 13 remains closed by the first valve body15, thereby coming to a small flow rate control state in which the flowrate of the refrigerant (the opening degree of the second control valve)is controlled in correspondence to a lift amount of the second valvebody 24. In this small flow rate control state, the refrigerant at acorresponding amount to the lift amount of the second valve body 24flows to the inflow port 5→the first valve chamber 11→the vertical holecommunication path 29→the second valve chamber 21→the second valve port23→the outflow port 6.

Further, if the lift amount of the second valve body 24 goes beyond thepredetermined amount Tc, the retaining shoulder surface 25 g of theintermediate large diameter portion 25 f comes into contact with thelower surface of the upper side portion 27 a of the pilot valve bodyretention member 27 and the pilot valve body retention member 27 and thepilot valve body 20 are pulled up against the energizing force of thepilot valve closing spring 26A, as shown in FIG. 3, whereby the pilotpassage 19 is opened and the pressure in the back pressure chamber 16 isreleased to the outflow port 6 via the pilot passage 19. As a result,the pressure of the back pressure chamber 16 falls down, the valveopening force becomes finally larger than the valve closing force whichacts on the first valve body 15, and the first valve body 15 movesupward so as to open the first valve port 13, thereby coming to thelarge flow rate control state in which the refrigerant flows to theinflow port 5→the first valve chamber 11→the first valve port 13→theoutflow port 6. In this case, FIG. 3 shows the maximum lift state of thesecond valve body 24 in which the upper side portion 27 a of the pilotvalve body retention member 27 comes into contact with the ceilingsurface 21 a of the second valve chamber 21.

As is understood from the description mentioned above, in the compositevalve 1 in accordance with the present embodiment, since it isstructured such as to be provided with the pilot valve body 20 which isindependent from the second valve body 24, in addition to the firstcontrol valve 4A (the first valve body 15 and the first valve port 13)for the large flow rate, and the second control valve 4B (the secondvalve body 24 and the second valve port 23) for the small flow rate, anddrive the pilot valve body 20 so as to open and close by utilizing theelevating motion of the valve shaft 25 which is provided with the secondvalve body 24, it is possible to set the dimension and the shape of thesecond control valve 4B (the second valve body 24 and the second valveport 23) for the small flow rate to ones which are optimum for the smallflow rate control, and it is possible to securely carry out the openingand closing of the first control valve 4A for the large flow rate at thedesired timing. Further, since the refrigerant is structured such as tobe circulated without being passed through the narrow portion such asthe sliding surface gap or the like as is different from theconventional structure at a time of the small flow rate control, it ispossible to make the malfunction hard be caused. As a result, it ispossible to achieve both of an improvement of the flow rate controlprecision in the small flow rate region and an increase of thecontrollable flow rate (a reduction of the pressure loss) withoutcausing an increase of the motion load and an enlargement in size of thedriving portion (the motor portion) and the valve main body.

In addition, the composite valve 1 in accordance with the presentembodiment, since the second valve port 23 which is opened and closed bythe second valve body 24 is communicated with the outflow port 6, andthe composite valve 1 is provided with the vertical hole communicationpath 29 which communicates the first valve chamber 11 with the secondvalve chamber 21, and is structured such that the high pressure in thefirst valve chamber 11 is introduced into the second valve chamber 21,the valve closing force (the pushing down force) acting on the secondvalve body 24 in the valve closing state becomes significantly largerthan the force which is going to push up it. Therefore, it is possibleto securely prevent the second valve body 24 from opening the valveundesirably without enlarging the spring load of the valve closingspring (reference numeral 34 in FIG. 4) which energizes the second valvebody 24 (the valve shaft 25) in the valve closing direction, and it ispossible to reduce the constraint with respect to the bore diameter ofthe second valve port 23 or the like. As a result, it is possible toachieve a cost reduction, a downsizing and a reduction of an electricpower consumption.

Further, in the composite valve 1 in accordance with the presentembodiment, since the pilot valve fitting and inserting hole 20 isformed in the lower surface of the second valve chamber 21 to which thehigh pressure of the first valve chamber 11 is introduced, and the pilotpassage 19 which communicates the back pressure chamber 16 with theoutflow port 6 is structured such as to be opened and closed by thepilot valve body 20 which is slidably fitted and inserted to the pilotvalve fitting and inserting hole 20 from the second valve chamber 21.Accordingly, the high pressure of the first valve chamber 11 and thesecond valve chamber 21 is applied to the other portions than the lowersurface portion of the pilot valve body 20 (the semispherical valve bodyportion 20 a which occludes the downstream vertical hole 19 b).Therefore, it is possible to securely prevent the pilot valve body 20from opening the valve undesirably without enlarging the spring load ofthe pilot valve closing spring 26A which energizes the pilot valve body20 in the valve closing direction, and it is possible to reduce theconstraint with respect to the inner diameter of the pilot passage 19and the bore diameter of the pilot valve seat (the opening portion ofthe downstream vertical hole 19 b which is occluded by the semisphericalvalve body portion 20 a) in the same manner as the case of the secondvalve body 24 (the valve shaft 25). As a result, it is possible toachieve a cost reduction, a downsizing, a reduction of the electricpower consumption and the like.

In this case, it goes without saying that the composite valve inaccordance with the present invention is not limited to the structure ofthe composite valve 1 in accordance with the first embodiment mentionedabove, but various modifications can be applied thereto.

For example, in the embodiment mentioned above, the pressure equalizinghole 17 is provided in the first valve body 15, as the means forpressure equalizing the first valve chamber 11 and the back pressurechamber 16, however, the pressure equalizing means is not limited tothis embodiment, but may be structured such that a small gap is providedbetween the piston ring 15 f which is provided in an outer periphery ofthe large diameter portion 15 a of the first valve body 15, and (theinner wall surface of) the fitting and inserting chamber 14, and the gapis set to the pressure equalizing means.

Further, the description is given on the assumption that the first valvechamber 11 and the second valve chamber 21 are communicated by thevertical hole communication path 29, however, the present invention isnot limited to this embodiment, but may be structured such that theinflow port 5 and the second valve chamber 21 are communicated.

Further, it goes without saying that the composite valve in accordancewith the present invention is not only applied to the heat pump typecooling and heating system, but also may be applied to the othersystems.

What is claimed is:
 1. A composite valve comprising: a first valve body;a valve shaft which is provided with a second valve body; an elevationdriving means for moving up and down said valve shaft; a pilot valvebody which is driven so as to be opened and closed by utilizing anelevating motion of said valve shaft; and a valve main body which isprovided with an inflow port and an outflow port, wherein between saidinflow port and said outflow port in said valve main body, there areprovided a fitting and inserting chamber to which said first valve bodyis slidably fitted and inserted, and which is zoned into a back pressurechamber and a first valve chamber by said first valve body, a firstvalve port which is open to said first valve chamber, a second valvechamber in which said pilot valve body and said second valve body arearranged so as to be movable up and down, a communication path whichcommunicates said inflow port or said first valve chamber with saidsecond valve chamber, a second valve port which communicates said secondvalve chamber with said outflow port, and a pilot passage whichcommunicates said back pressure chamber with said outflow port, whereinsaid first valve body and said second valve body are arranged in such amanner as to be moved up and down in the same direction, and are awayfrom each other only at a predetermined distance, and wherein in thecase that a lift amount of said second valve body is equal to or lessthan a predetermined amount, said pilot passage is closed by said pilotvalve body, and said first valve port is closed by said first valvebody, thereby taking a small flow rate control state in which a flowrate is controlled in correspondence to said lift amount of said secondvalve body, and in the case that said lift amount of said second valvebody goes beyond said predetermined amount, said pilot valve body ismoved up in conjunction with the upward movement of said valve shaft soas to open said pilot passage, thereby taking a large flow rate controlstate in which said first valve body opens said first valve port.
 2. Acomposite valve as claimed in claim 1, wherein said pilot valve isenergized downward by a spring member so as to close said pilot passage,and is pulled up against the energizing force of said spring member by acatch portion which is provided in said valve shaft, if the lift amountof said second valve body is increased further more than saidpredetermined amount.
 3. A composite valve as claimed in claim 1,wherein said first valve body is provided with a pressure equalizinghole which communicates said first valve chamber with said back pressurechamber.
 4. A composite valve as claimed in claim 2, wherein said firstvalve body is provided with a pressure equalizing hole whichcommunicates said first valve chamber with said back pressure chamber.